/*
 * Copyright 2012-2018 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      https://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package cn.springcloud.gray.bean.properties;

import java.lang.annotation.Annotation;
import java.lang.reflect.Method;
import java.util.HashMap;
import java.util.Map;
import java.util.concurrent.atomic.AtomicReference;

import org.springframework.beans.BeansException;
import org.springframework.beans.factory.config.BeanDefinition;
import org.springframework.beans.factory.config.BeanFactoryPostProcessor;
import org.springframework.beans.factory.config.ConfigurableListableBeanFactory;
import org.springframework.core.annotation.AnnotationUtils;
import org.springframework.util.ClassUtils;
import org.springframework.util.ReflectionUtils;

/**
 * Utility class to memorize {@code @Bean} definition meta data during initialization of
 * the bean factory.
 *
 * @author Dave Syer
 * @since 1.1.0
 */
public class ConfigurationBeanFactoryMetadata implements BeanFactoryPostProcessor {

    /**
     * The bean name that this class is registered with.
     */
    public static final String BEAN_NAME = ConfigurationBeanFactoryMetadata.class
            .getName();

    private ConfigurableListableBeanFactory beanFactory;

    private final Map<String, FactoryMetadata> beansFactoryMetadata = new HashMap<>();

    @Override
    public void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory)
            throws BeansException {
        this.beanFactory = beanFactory;
        for (String name : beanFactory.getBeanDefinitionNames()) {
            BeanDefinition definition = beanFactory.getBeanDefinition(name);
            String method = definition.getFactoryMethodName();
            String bean = definition.getFactoryBeanName();
            if (method != null && bean != null) {
                this.beansFactoryMetadata.put(name, new FactoryMetadata(bean, method));
            }
        }
    }

    public <A extends Annotation> Map<String, Object> getBeansWithFactoryAnnotation(
            Class<A> type) {
        Map<String, Object> result = new HashMap<>();
        for (String name : this.beansFactoryMetadata.keySet()) {
            if (findFactoryAnnotation(name, type) != null) {
                result.put(name, this.beanFactory.getBean(name));
            }
        }
        return result;
    }

    public <A extends Annotation> A findFactoryAnnotation(String beanName,
                                                          Class<A> type) {
        Method method = findFactoryMethod(beanName);
        return (method != null) ? AnnotationUtils.findAnnotation(method, type) : null;
    }

    public Method findFactoryMethod(String beanName) {
        if (!this.beansFactoryMetadata.containsKey(beanName)) {
            return null;
        }
        AtomicReference<Method> found = new AtomicReference<>(null);
        FactoryMetadata metadata = this.beansFactoryMetadata.get(beanName);
        Class<?> factoryType = this.beanFactory.getType(metadata.getBean());
        String factoryMethod = metadata.getMethod();
        if (ClassUtils.isCglibProxyClass(factoryType)) {
            factoryType = factoryType.getSuperclass();
        }
        ReflectionUtils.doWithMethods(factoryType, (method) -> {
            if (method.getName().equals(factoryMethod)) {
                found.compareAndSet(null, method);
            }
        });
        return found.get();
    }

    private static class FactoryMetadata {

        private final String bean;

        private final String method;

        FactoryMetadata(String bean, String method) {
            this.bean = bean;
            this.method = method;
        }

        public String getBean() {
            return this.bean;
        }

        public String getMethod() {
            return this.method;
        }

    }

}
